I will be running a Kifaru EMR II this year up in AK for moose and caribou. I wanted a big enough bag with multiple pockets to stash gear in while being able to leave the main pack compartment open for back moose meat. I do believe the front zip is paramount when hauling massive amount of meat and many many loads, being able to unzip and load and unloaded without to much work will save energy for the next load. The plan is to Tag Bag the boned out meat and then put in a leak proof bag then into the pack and synch down all the load straps and threw the brush we shall go. I have attached a couple pics of a bull we helped pack out a couple miles at 12-13K elevation with a couple timberline packs. My back was full of an entire rear quarter boned out and some neck meat, Aron's pack was stuffed with the entire cape for a life sized mount. If I remember correctly Aron's pack was pushing 160lbs. Both loads proved to be very stable and rode very comfortable, I prefer packing meat in the pack and strapping it down securely. Goodluck to everyone this season!
I don't use a bag on the frame when packing out moose. An integrated meatshelf and 2-3 straps with buckles hold on each bagged portion of meat.
I take each portion and put it in a regular game bag then put that in an outer bag that was made from a old duffel. Then strap the whole thing to the pack frame as it sits on the meat shelf. Done. Zero issues. I take the meat bag out of the duffel at camp and go for another load.
That's my method. Might not work fro everyone, but works for me.